Its only role should be to defuse situations before they spiral out of control, writes John O'Shea.
Three-and-a-half million people in eastern Congo and a further 2½ million in Darfur, western Sudan, are currently facing disaster. Far more than humanitarian aid, however, it is military protection they need.
That might seem a shocking thing for the CEO of an aid organisation to advocate, but the sensible and timely deployment of troops can often save more lives than humanitarian aid.
If left to their own devices the people in the Congo and Darfur would be planting their crops and generally getting on with their lives now. Instead, they have fled their homes in search of sanctuary from the violence that has erupted around them.
These are but two of the 70 or so conflicts in the world at the moment, some of which are afforded blow-by-blow coverage in the media while others go almost unnoticed.
Whatever the level of publicity, military conflict is increasingly impacting on civilian populations.
Life was never easy in Darfur, but for years the people there have managed to scrape a sparse existence from subsistence farming. When armed conflict broke out some 18 months ago, their lives were immediately made impossible.
Driven out of their villages by militias of nomadic Arabic tribesmen called Jinjaweeds, who employ such basic tactics as rape, theft and murder and who are reportedly armed and encouraged by the mainly Arab government of Sudan, the black African people have had to flee, leaving their crops to rot in the ground or be stolen.
Their land is now being grazed by the militiamen's cattle and camels.
Between two and three million people are living rough in this region, which is burning hot by day and bitterly cold at night.
They huddle together for company and the illusion of safety in grossly overcrowded and under-resourced camps or they take their chances by hiding out in the countryside. Many thousands more have managed to cross the border into neighbouring Chad.
This is where the problem lies for the aid agencies - because of the fighting many of these people are beyond our reach. We simply cannot help them. Aid organisations cannot function in such circumstances; unless the landmines are cleared we cannot consider mounting rescue operations.
The only force that can stop the fighting in such circumstances would be a properly equipped military organisation with an international mandate to enforce peace for the sake of humanity.
I say "would be" because, unfortunately for many millions of people around the world who find themselves caught up in conflict and cut off from humanitarian assistance, such a force does not exist.
We have the UN and NATO, and a European army is about to be raised; an African army is also being mooted; but none of these has succeeded, or is likely to succeed, in protecting the vulnerable because none of them has that as its sole objective and none is able to get to the trouble spot at a moment's notice.
I have often come across disasters that could have been nipped in the bud had someone had the common sense and foresight to send in such a peacekeeping force. Many millions of people have died needlessly as a direct result.
The G8 summit in Georgia came up with a plan to train a 75,000-strong peacekeeping force for Africa, a continent that seems to be constantly at war.
But perhaps a totally African force is not such a good idea. Some of the disputes that it might be called on to police could be too close to home for some of the commanders to take a neutral stance.
It would surely be far better for the international community to establish a truly international force with troops supplied from all over the world.
Their only criteria should be to defuse situations before they spiral out of control.
Such a peacekeeping force should be truly international in its make-up and be drawn up by the United Nations to be kept in readiness to respond quickly before civilians are adversely affected.
The ability to respond quickly is the key to saving lives. The Rwandan genocide cost a million lives but took just 100 days to carry out.
As any fire officer in the world will tell you, money spent on fire prevention is far more important than that spent on firefighting. So it is with international peacekeeping. It is far better to concentrate on preventing life-threatening situations developing than to mount humanitarian operations to mop up the resulting mess.
Again, western Sudan is a classic case. If a totally neutral armed force was deployed it could prevent the militias from attacking civilians, who would feel safe in their homes and would now be farming their land rather than sitting in dreadful camps praying that the international aid agencies reach them before the militia.
In the Ethiopian famine of 1984 troops could have saved many lives had they been used to get aid more widely distributed.
An international force might have stopped the suffering in Pol Pot's killing fields, or prevented Idi Amin from carrying out his atrocities in Uganda, and millions of people could have been saved in the Congo.
We have a responsibility to help the vulnerable when they face hardship, but we also have a responsibility to do what we can to prevent their situation descending into the hell of Darfur, Rwanda, Somalia or Congo.
Such a force could save millions of lives each year and allow humanitarian organisations to get on with the myriad other problems afflicting the poor, such as the HIV/AIDS crisis, the lack of clean water, malaria, poor housing and lack of education and training.
The "to do" list is long enough without having to clean up after yet another war.